Some statements may merely provide background information related to the present disclosure and may not constitute prior art.
Gelled liquid hydrocarbon fluids have been utilized in treating subterranean formations penetrated by well bores, e.g., for stimulation or sand control treatments such as fracturing or gravel packing, respectively. In fracturing treatments, a gelled liquid hydrocarbon fracturing fluid that may comprise particulates, often referred to as proppant, suspended therein is pumped through a well bore into a subterranean formation at a rate and pressure such that one or more fractures are formed or enhanced in a portion of the formation. Proppant particulates may be deposited in the fractures, inter alia, to prevent the formed fractures from closing, thereby maintaining conductive channels through which produced fluids can flow to the well bore. At a desired time, the viscosity of the gelled liquid hydrocarbon fluid may be reduced or “broken” and the fluid may be recovered.
Similarly, sand control operations, such as gravel packing, use gelled liquid hydrocarbon fluids, often referred to as gravel pack fluids. Gravel pack fluids usually are used to suspend gravel particulates for delivery to a desired area in a well bore, e.g., near unconsolidated or weakly consolidated formation particulates, to form a gravel pack to enhance sand control. One common type of gravel packing operation involves placing a gravel pack screen in the well bore and packing the annulus between the screen and the well bore with gravel of a specific size designed to prevent the passage of formation sand. The gravel, inter alia, acts to prevent the particulates from occluding the screen or migrating with the produced fluids, and the screen, inter alia, acts to prevent the gravel from entering the production tubing. Once the gravel pack is substantially in place, the viscosity of the gravel pack fluid often is reduced to allow it to be recovered or produced back from the well bore.
Polyvalent metal salts of orthophosphoric acid esters have been utilized as gelling agents for forming high-viscosity gelled liquid hydrocarbon treatment fluids. Such gelled liquid hydrocarbon treatment fluids often have included particulate materials such as proppant or gravel, and oftentimes delayed breakers for causing the treatment fluids to break into relatively thin fluids so that the treatment fluids may be produced back. Good descriptions of these processes, specifically utilizing aluminum (Al3+) salts of the orthophosphate esters, may be found in the following patents: Griffin U.S. Pat. No. 4,174,283, Burnham and Tiner U.S. Pat. No. 4,200,539, Burnham U.S. Pat. No. 4,200,540, Burnham U.S. Pat. No. 4,316,810, and Harris, Hottmeyer and Pauls U.S. Pat. No. 4,622,155. Fracturing processes utilizing iron compounds in combination with similar orthophosphate esters are described by Monroe in U.S. Pat. No. 3,505,374, by Smith and Persinski in U.S. Pat. No. 5,417,287 and by Smith et al. in U.S. Pat. No. 5,846,915. All of these patents being herewith incorporated by reference. The gelled liquid hydrocarbon fracturing fluids described in the above patents utilize ferric iron (Fe3+) or aluminum polyvalent metal salts of phosphoric acid esters as gelling agents and delayed breakers such as hard burned magnesium oxide which is slowly soluble in water.
While the heretofore utilized high viscosity gelled liquid hydrocarbon fracturing fluids and methods have been used successfully for forming fractures in subterranean formations, sometimes problems have been encountered as a result of the use of the gelling agent, i.e., the ferric iron salt of a phosphoric acid ester.
Thus, there are needs for improved methods of using and preparing gelled liquid hydrocarbons, improved liquid hydrocarbon gelling agents, and improved gelled liquid hydrocarbon compositions.